It’s no secret that as you get older, belly fat becomes increasingly difficult to get rid of. Not only is belly fat problematic for clothing and bathing suit season, but it can also lead to chronic diseases and cardiovascular issues. For years, scientists have struggled to determine why this specific type of fat seems to accumulate as we age.
But now, a new study from Yale has identified how the nervous and immune systems controlling inflammation and metabolism cause belly fat.
The results help explain why belly fat isn’t burned off as efficiently in older adults and could lead to new therapies for targeting harmful belly fat stores.
The study was led by Vishwa Deep Dixit, a professor of Comparative Medicine and Immunobiology, and was published in the journal Nature.
Dixit and his team first looked at immune cells known as macrophages, which are helpful in fighting infections, and found a new type of macrophage located in nerves in belly fat.
These new macrophages become inflamed over time and hinder the proper function of the neurotransmitters.
The researchers then studied immune cells from fat tissue in mice to further understand how the macrophages increase belly fat storage.
“We discovered that the aged macrophages can break down the neurotransmitters called catecholamines, and thus do not allow fat cells to supply the fuel when demand arises,” said Dixit.
Dixit and his team were able to successfully target specific receptors that control inflammation and lower them in the older mice. This receptor is known as the NLRP3 inflammasome, and by lowering it, fats were broken down more efficiently, like in the younger mice.
In another experiment, Dixit blocked an enzyme that increased in the aged macrophages and this also helped enhance metabolic breakdown of fat.
Certain drugs that currently treat depression also inhibit this enzyme. But further studies will have to be done to see if results can be replicated in humans to reduce belly fat, and if using enzyme inhibiting drugs like the ones used for depression would be safe and effective.
The researchers gained a better understanding of why belly fat stores do not burn off in older adults and could potentially help create new therapies for targeting and reducing harmful belly fat.